Gunning nozzle shield



Jan. 16, 1968 J. BOWMAN 3,363,839

GUNNING NOZZLE SHIELD Filed Nov. 8, 1965 INVENTOR. JAN BOWMAN ATTORNEY United States Patent 3,363,839 GUNNING NOZZLE SHIELD Jan Bowman, Los Gatos, Califi, assignor to Kaiser Alumnnum & Chemical Corporation, Oakland, Calif., a corporation of Delaware Filed Nov. 8, 1965, Ser. No. 506,764 4 Claims. (Cl. 239-103) ABSTRACT OF THE DISCLOSURE Rebound and dusting while gunning a fluent granular material onto a target surface are reduced when the gun nozzle is surrounded by a cylindrical shield having holes in the portion opposite the nozzle, the open end of the shield being held against the target surface.

This invention concerns a method and means for placing fluent materials.

It has lOng been customary to place a fluent material, for example concrete, by mixing the solids, for example Portland cement, sand, and aggregate, with water and casting the resulting slurry into forms. In recent years, it has also become common to place fluent materials, for example granular refractory mixes containing a binder or cement, by projecting them through a nozzle or gun and onto a wall or other structure in which they are to be used, water being admixed with the dry granular solids just prior to projection from the gunning nozzle. This method has the advantage of rapidly and economically conveying the material to its ultimate location without the use of mechanical conveyors or hoppers or wheelbarrows and effecting the admixture of water Without using batch mixers.

However, one of the problems occurring with the gunning method of placing fluent granular materials is that there is considerable rebound or dusting. In other words, some of the material does not stay in place where it has been projected but bounces off as a dust or spray and is generally lost. This causes variations in sizing and composition of the material and decreases its strength and density.

There has now been discovered, according to this invention, a method and means for reducing and prac tically eliminating the amount of rebound material when fluent solids are placed in a form or elsewhere by the gunning method of projection. The following specific description of one embodiment of the present invention is intended by way of illustration and not as limiting of the scope of the invention.

The drawing shows a side elevational view of an apparatus according to this invention. The apparatus comprises a conventional gunning nozzle 11 to which fluent granular material is conveyed through hose 12, for example by compressed air. Water, supplied to the apparatus through line 13, is admixed with the solid granular material at a water ring 15, the flow of water being controlled by valve 14. The wetted admixture is then projected out through opening 16 in nozzle 11. The gunning nozzle, water ring, water valve, and associated feed lines are conventional and any such apparatus known in the art can be used in the practice of this invention.

Attached to the gun is a tubular member 17 which is of substantially constant or uniform cross-sectional area and shape from end to end. Conveniently, it will be of circular cross-section and can be made, for example, of sheet metal. Tubular member 17 has a lower open end 20 and an upper closed end 19 through which gun nozzle 11 enters. It also contains side openings 21, located in its wall and placed adjacent upper end 19. Tubular member 17 is placed so that gun nozzle 11, and particularly Patented Jan. 16, 1968 exit 16 therefrom, lies within tubular member 17. More specifically exit 16 lies at a point within tube 17 more remote from end 19 than are holes 21. Thus, when fluent material is discharged from exit 16 of nozzle 11, it is discharged within tubular member 17, which is firmly aflixed to nozzle 11. Preferably, nozzle 11 is placed concentrically within tubular member 17, particularly when the tubular member is of circular cross-section.

In using the apparatus illustrated, open end 20 of tubular member 17 is placed against the surface onto which fluent material is to be projected. Fluent material is then projected from the gun to the nozzle and through tubular member 17, striking the target surface. A form 18 is shown in the drawing. It is essential that end 20 be kept up against the target surface, which will, after some material has been placed, be fluent material already in position.

When tubular member 17 is in this position, the air which accompanies the fluent material, having been used to project it through hose 12, and onto the target surface, is forced to leave tubular member 17 through openings 21.

When this method of operation is used, it is found that rebound of the projected material is substantially eliminated and that the air escaping from the region of projection does not carry with it any of the fine granular material. Not only does this prevent waste of material projected, but also helps to maintain a clear and unfogged atmosphere in the vicinity of the gunning operation. This method of operation also prevents segregation of the coarse and fine components of the projected fluent solid material. The placed material can be left as placed or subsequently vibrated or rammed in place to achieve maximum strength and density.

While this apparatus and the method of using it have been found to be particularly useful in gunning fluent refractory materials, for example to form a monolithic hearth in an open hearth steel making furnace, it will be understood that they can be used Whenever it is desired to project fluent granular materials, such as structural concrete, by the gunning method.

While it has been said that end 20 of tubular member 17 will be maintained in contact with the surface against which the fluent material is projected, it will be understood that it is possible for the end of tubular member 17 to project into or he below the surface 23 of material already placed, as is shown in the drawing.

While the dimensions of the apparatus are not critical, it has been found to be particularly effective when the area of openings 21 are about sixteen times the area of nozzle exit 16, and when the cross sectional area of tube 17 is about 40 times the area of nozzle opening 16.

What is claimed is:

1. A device for placing wetted fluent granular solid material comprising:

(1) a conduit through which dry granular material can be fluently conveyed, said conduit having an entrance end and an exit end;

(2) means in the conduit adjacent the exit end thereof adapted to introduce water into dry granular solid material being fluently conveyed through said conduit; and

(3) a hollow tubular member having a closed upper and an open lower end; and side wall openings adjacent the upper end, said tubular member being disposed about the exit end of the conduit so that the conduit exit lies within the tubular member and is located at a point more remote from the upper end of said tubular member than any portion of said side wall openings.

2. A device as in claim 1 wherein said tubular member 1s of larger internal cross sectional area than said nozzle and is of uniform cross sectional area and shape, and

is disposed concentrically about said nozzle.

said side openings are symmetrically placed about the References Cited Wall of said tubular member. UNITED STATES PATENTS 3 A device as in claim 2 wherein said tubular mem er ,6 8/ 937 Fri drich W 169 15 X 4. A device as in claim 2 wherein the cross sectional 5 2,761,516 9/1956 Vassilkovskyarea of said tube is about 40 times the area of the nozzle exit and the total area of said side openings is about 16 HENSON WOOD Examine times the area of the nozzle exit. H. NATTER, Assistant Examiner. 

